Axial Ribs for Crack Control in Turbine Guide Vanes
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Solution Overview
Problem
Guide vane arrangements in aircraft engine gas turbines face high thermal loads, leading to potential component cracks due to cooling slits, which are a source of crack propagation.
Innovation Solution
The implementation of axial ribs on the external shroud band, extending radially outward and connected to the circumferential surface and radial flanges, controls and limits crack propagation by directing it to favorable regions, minimizing material costs and preventing crack crossover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling slits are provided in the radial flange to cool the guide vane arrangement, then cooling efficiency is improved, but crack propagation risk increases
Solution Approach 1:
The axial ribs are strategically positioned to extend to the radially inner end of cooling slits, converting the harmful notch effect at slit ends into a beneficial crack arrest mechanism. The ribs act as barriers that stop crack propagation while maintaining the cooling function of the slits.
Solution Approach 2:
The axial ribs serve as intermediary structures between the cooling slits and the circumferential surface, mediating the stress distribution and preventing direct crack propagation from the slit ends into critical regions of the guide vane arrangement.
2Reliability
If axial ribs are added to control crack propagation, then structural integrity is improved, but device complexity increases
Solution Approach 1:
The external shroud band is segmented by adding axial ribs that divide the structure into distinct regions. These ribs create segmented zones that independently manage crack propagation, with each rib acting as a separate barrier element.
Solution Approach 2:
The axial ribs are positioned specifically at critical locations where crack propagation is most likely to occur, particularly at the radially inner ends of cooling slits. This localized reinforcement provides enhanced crack control only where needed, rather than uniformly throughout the entire structure.
Data Source
AI summary
A guide vane arrangement for a turbomachine, particularly a gas turbine, is disclosed. The guide vane arrangement includes an external shroud band, on which at least two guide vanes protrude radially inward. A pair of axial ribs spaced apart from each other in the peripheral direction and disposed between two adjoining guide vanes in the peripheral direction protrude radially outward from a circumferential surface of the external shroud band and/or axially from a radial flange of the external shroud band.